1. Field of the Invention
The present invention relates to a technique for driving a brushless DC motor and, more particularly, to a technique for preventing the breakdown of a circuit for driving a motor if a short circuit occurs in the motor.
2. Description of the Background Art
A three-phase brushless DC motor, for example, is driven in response to three-phase current supplied thereto from a three-phase output circuit or drawn therefrom to the three-phase output circuit.
Unfortunately, if any exciting coil for one phase in the three-phase brushless DC motor is shorted to a ground potential or a power supply potential, the three-phase output circuit supplies an excessively greater amount of current than that during normal operation. This results in the thermal breakdown of the three-phase output circuit.